Premium Quality 51625A Tri-Color Inkjet Cartridge compatible with the HP C2121A, DeskJet 200, 310, 311, 320, 340, 400, 420, 500, 520, 540, 550c, 560, Portable, DeskWriter 310, 320, 340, 400, 500c, 510, 520, 540, 550, 560, C Also fits Encad, Novajet, Xerox, Apollo, and Summagraphics. The use of compatible supplies does not void your printer warranty. Product Detail Ninestartechonline.com